Japanese Patent Application Laid-Open No. 354086/1992 and Japanese Patent Application Laid-Open No. 165883/1994 disclose play toys that provide a barcode indicated on an article and a barcode reader for reading the barcode to develop play based on the barcode readout result. For example, the art disclosed in the Japanese Patent Application Laid-Open No. 165883/1994 employs a CCD camera as a barcode sensor for a barcode reader. Also, the art disclosed in the Japanese Patent Application Laid-Open No. 354086/1992, in addition to a barcode sensor, uses a proximity sensor to eliminate problems caused by a small displacement.
Patent document 1: Japanese Patent Application Laid-Open 354086/1992
Patent document 2: Japanese Patent Application Laid-Open 165883/1994